As a conventional audio signal decoding method and a coding method, there exists the ISO/IEC International Standard schemes; that is, the so-called MPEG schemes. Currently, as a coding scheme which has a wide variety of applications and provides a high quality even with a low bit rate, there exists the ISO/IEC 13818-7; that is, the so-called MPEG-2 Advanced Audio Coding (AAC) scheme. Expanded standards of the scheme are currently being standardized (refer to Reference 1).
Reference 1: ISO/IEC 13818-7 (MPEG-2 AAC)